In several interviews the Air Force conducted of fellow pilots as well as his superiors, Haney was described as an exceptional pilot -- "above average" when it came to most fighter pilot duties and one of the service's best. Two years before the crash, he had scored an "A" when tested on emergency systems and survival.

"He was kind of one of the more quiet guys in the squadron... [but] when he would speak, he would choose his words carefully and he normally said something worth listening to," Haney's squadron commander told investigators. "I think he was very happy. He struck me as a guy that was a natural fighter pilot that liked doing what he was doing and was very content."

The F-22 Raptor has had a history of apparent oxygen problems. Since 2008 pilots have reported more than a dozen instances of experiencing hypoxia-like symptoms mid-flight, according to the Air Force. The Air Force grounded the entire fleet of planes for nearly five months in 2011 while it investigated the possible cause of the problem but were never able to identify it and cautiously have allowed the planes back in the air. Those pilots, however, did not suffer a complete oxygen shut-off like Haney did and were able to guide the planes back to base without incident.

The Air Force maintains that Haney was never incapacitated during the flight, despite a period of several seconds when he did not touch the plane's controls in the midst of his deadly freefall. Investigators said that Haney simply was too distracted by being not able to breathe to fly the plane.

But one of Haney's fellow pilots has another theory -- one that may never be public because it was omitted from official account. The pilot had chosen to share it with Air Force investigators off the record, the documents obtained by ABC News said.

Despite going combat operational in 2005, the F-22 Raptor has not seen combat and was not considered "an operational necessity" in any theater of combat from Libya to Iraq and Afghanistan, the Air Force said.